Sometimes air will get in the system and cause bubbles but it is rare. With 134A the loss and or no bubbles don't give you a charge indication. That was a carry over from R-12 freon. The ONLY way to check proper charge is with a set of gauges hooked to the suction and discharge lines.
The reason it operates a little better at night is the temperature of the refrigerant is lower with allows the super heat conduction to be better. You can achieve the same thing by running water on your condenser. That alone tells me you have a low refrigerant charge. Classic AC operation. Good luck
Wednesday, May 31st, 2006 AT 4:02 PM